Welding gun attachment mechanism

ABSTRACT

A power block for holding a welding gun power pin has a receiving structure which defines a bore which receives and holds a welding gun power pin. The power block further includes a projection movable between at least a first position and a second position. When the projection is in the first position, the projection extends at least partially into the receiving structure cavity. When the projection is in the second position, the projection generally does not extend into the receiving structure cavity. In some embodiments, the projection has a generally straight line distal edge. In other embodiments, the projection has a generally arcuate distal edge.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part application claiming priorityunder 35 U.S.C. 120 to U.S. application Ser. No. 10/820,996, filed Apr.8, 2004, and U.S. application Ser. No. 10/820,997, filed Apr. 8, 2004,both of which are incorporated by reference in their entireties.

BACKGROUND

The present invention relates generally to welding systems, and moreparticularly, to apparatus for feeding welding wire in welding systems.

An important part of welding systems is the mechanism that feeds anelectrode wire, a filler-material wire, or other weld wire to the workpiece. Weld wires range in size and in material composition. Typically,weld wires range in size from approximately 0.023 inch in diameter toapproximately 0.052 inch in diameter and can be as large asapproximately 0.250 inch in diameter, and include material compositionsof steel, stainless steel, aluminum, and/or other materials.

As used herein, the phrase “wire feeder assembly” includes a spool ofweld wire, a drive assembly, any gun liner, and any other support orcontrol apparatus along the path of travel of the wire between the spooland the contact tip of the gun, including the electronic controls.

Wire feeder assemblies generically comprehend electrode wire feedersused in e.g. Gas Metal Arc Welding (GMAW) in which the electrode wire isfed as part of the welding circuit and melts to become part of the welddeposit/pool. Wire feeder assemblies also include cold wire feeders usedin e.g. Gas Tungsten Arc Welding (GTAW) and laser welding in which thefiller-material wire is fed into, and melts from the heat of, the weldpool and thus becomes part of the weld pool.

In addition, wire feeder assemblies and/or components thereof can beused to drive materials other than weld wire, such materials typicallyhaving generally physically similar characteristics and/or properties tothose of weld wire.

The drive assembly typically includes an electric motor which drives arotationally-driven drive roll, which cooperates with a correspondingpressure roll. Both the rotationally-driven drive roll and the pressureroll, e.g. a pressure drive roll, cooperate in driving the weld wire.The rotationally-driven drive roll and the pressure drive roll haveouter circumferential surfaces, at least one of the drive roll andpressure drive roll having a groove formed therein sized and configuredto accept a weld wire having a particular diameter, between thecooperating drive rolls.

The pressure drive roll applies lateral pressure against the weld wireand correspondingly against the rotationally-driven drive roll. When theelectric motor is energized, it rotationally drives therotationally-driven drive roll which, in cooperation with the pressuredrive roll, advances the weld wire through the liner and contact tip inthe welding gun, and into the weld pool.

The drive assembly can jam if the weld wire strays from the desired feedpath which extends through the e.g. nip which is defined between theupper and lower drive rolls. Wire jams can be caused when the weld wirecollapses as the compressive columnar strength of the weld wire isexceeded, whereupon the weld wire becomes bunched up, tangled, wrappedaround drive rolls, or other components in the drive assembly, orotherwise travels along a non-desired path or deviates from the desiredpath. In any case, such deviant wire travel is sometimes referred to ase.g. “bird's nesting.”

“Bird's nesting” normally occurs in an area in which the weld wire isunsupported, and typically happens when the weld wire drag, orresistance to movement through the liner, combines with the weld wiredriving force applied by the drive rolls to overcome the columnarstrength of the wire. When the columnar strength is exceeded, the weldwire ceases movement through the conduit, and piles up in the area ofcollapse, or travels along a non-desired path until the electric motordriving the drive rolls ceases its drive action.

“Bird's nesting” consumes operator/user time, requiring suchoperator/user to open the drive assembly and to untangle and/orotherwise clear the wire jam, and re-feed the weld wire along the wiredrive path.

It is not desirable to have an operator/user opening the drive assemblymore often than necessary, as many welding operations are performed inrather harsh environments and dirt and/or other debris frequently foundin such welding environments can eventually become lodged in e.g. theliner of the weld gun, which further compromises the travel of the weldwire to the workpiece.

When a wire jam occurs, the weld wire does not advance through the linerand contact tip of the welding gun. Thus the weld wire which extendsbeyond the contact tip is consumed without a new portion of the weldwire advancing to replace the consumed portion. This phenomenon iscommonly referred to as “burn-back” and can result in the weld wiremelting into, and thus becoming welded to, the contact tip of the gun.In the event where the weld wire becomes welded to the contact tip, theoperator/user typically must install a new contact tip before proceedingwith any more welding operations.

As weld wire is advanced along either a desired path e.g. out a weldinggun or along a non-desired path such as “bird's nesting,” the weld wirecan be energized by a welding power source. Accordingly, if the deviantweld wire comes into electrical contact with e.g. the electric motor ofthe drive assembly, the integrity of the electric motor can becompromised. Also, since such advancing weld wire is electrically“live,” a weld wire which advances along a non-desired path, for exampleoutwardly of the drive assembly, can pose safety hazards for theoperator and/or any persons near such activity.

Some weld wires are generally more susceptible to “bird's nesting” thanother weld wires. As one example, aluminum weld wires are moresusceptible to traveling along a non-desired path than are steel weldwires because aluminum has a relatively lower columnar strength and arelatively more easily deformable cross section, and/or relatively moremalleable.

Numerous approaches of dealing with “bird's nesting” problems in wirefeeders have been attempted, including use of TEFLON, and relativelyshorter liners in weld guns, and use of weld wire spool guns which areweld guns that house and drive a spool of weld wire in the gun itselfrather than having the weld wire spool mounted in combination with acontrol box. However, it is sometimes desirable to use a weld gun whichhas a relatively long liner to enable an operator/user to weld at apoint relatively distant from the weld wire feeder apparatus. Inaddition, weld wire spool guns are bulky in comparison to typical weldguns and accordingly can be relatively cumbersome to operate. Further,an operator/user may desire to weld with a spool of weld wire which islarger than that which can be housed in a weld wire spool gun, e.g. itmay be desirable to use a 12 inch spool of weld wire instead of a 4 inchspool.

It is desirable, therefore, to improve weld wire feeder assemblies toprovide more support for a weld wire in areas of the feeder assembliesin which a weld wire is typically unsupported. In addition, it isdesirable to improve weld wire feeder assemblies to provide a relativelymore consistent, and relatively more desirably distributed, pressure toa weld wire.

Another problem with typical weld wire feeder assemblies is that serviceand repair of the drive assembly can be difficult, especially in thefield. As one example, weld wire feeder assemblies having two drivemechanisms typically require at least some different components for e.g.left and right drive assemblies, which require storage of correspondingpiece-parts for each of the left and right drive assemblies.

Yet another problem with typical weld wire feeder assemblies is realizedat the interface between the weld wire feeder assembly and the “powerinterface” of the welding gun which is typically referred to as the“power pin.” Power pins are typically aligned with, and communicatewith, the weld wire feeder assembly to enable the weld wire, theelectrical power, and/or shielding gas, to pass therethrough. Typicalpower pins are clamped by a clamping mechanism to the weld wire feeder.Such power pin is known to be subjected to tension force, exerted alongthe longitudinal axis of the power pin, and tending to urge a withdrawalof the power pin from the weld wire feeder assembly. Known clampingmechanisms can, on occasion, provide insufficient clamping force againstthe tension being exerted on the power pin, and correspondingly thepower pin may respond with non-desired, at least partial, removal ordetachment of the power pin from the weld wire feeder assembly.

It is desirable, therefore, to improve the weld wire feeder assembly toprovide a weld wire feeder/power pin interface with a mechanicalinterface which further resists non-desired removal or detachment of thepower pin from the weld wire feeder assembly. It can also be desirableto provide a wire feeder/power pin interface having a selectablemechanical interface, so that a user can selectively choose to utilize,or not, such mechanical interface to further resist non-desired removalor detachment of the power pin from the weld wire feeder assembly asdesired.

As another example of needed improvements, changing drive rolls in somedrive assemblies requires tools. Certain known “tool-less” driveassembly designs require a dexterous manipulation of one or morecomponents of the drive assembly.

Therefore, it is also desirable to provide weld wire feeder assemblieswhich are easily serviced and/or repaired and which have drive assemblycomponents which are common to both left and right drive assemblies, andmethods and apparatus which facilitates easy removal and/or changing ofdrive rolls, other components, or consumable components, without usingtools.

It is also desirable to provide drive assemblies which require a coverto be closed over the internal components before operation of the driveassembly, which increases the probability of achieving a relativelyclean operational environment within the drive assembly.

It is also desirable to provide re-designed drive assemblies whichimpede the development of “bird's nesting,” and which facilitate thetravel of the weld wire along the desired path.

SUMMARY

A power block for holding a welding gun power pin has a receivingstructure which defines a receiving structure cavity. The power blockfurther includes a projection movable between at least a first positionand a second position. When the projection is in the first position, itextends at least partially into the receiving structure cavity. When theprojection is in the second position, it generally does not extend intothe receiving structure cavity. In some embodiments, the projectiondefines a generally planar profile. In other embodiments, the projectiondefines a generally arcuate profile.

According to another aspect of the invention, the power block isselectable between at least a first and a second configuration. In thefirst configuration, the receiving structure has a generally continuousinner circumferential surface. In the second configuration, thereceiving structure has a generally discontinuous inner circumferentialsurface.

Regardless, the power block, at least selectably, provides relativelyincreased resistance to non-desired power pin removal from the powerblock, as compared to a power block with only a clamping power pinattachment mechanism.

Other advantages, benefits, and features of the present invention willbecome apparent to those skilled in the art upon reading the detaileddescription of the illustrated embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a first embodiment of a weldingsystem which includes a wire feeder assembly of the present invention.

FIG. 2 shows a perspective view of a second embodiment of a weldingsystem which includes a wire feeder assembly of the present invention.

FIG. 3 shows a perspective view of a third embodiment of a weldingsystem which includes a wire feeder assembly of the present invention.

FIG. 4 shows a perspective view of a wire feeder assembly of the weldingsystem illustrated in FIGS. 1–2.

FIG. 5 shows an exploded view of a drive assembly of a wire feederassembly of FIG. 4.

FIG. 6A shows an exploded view of the carrier plate assembly illustratedin FIG. 5.

FIGS. 6B and 6C show enlarged perspective views of a second embodimentof a power block of the present invention.

FIG. 6D shows an enlarged perspective view of a third embodiment ofpower blocks of the present invention.

FIG. 7 shows an enlarged front elevation view of the isolation plateillustrated in FIG. 5.

FIGS. 8A, 8B, and 8C show enlarged perspective views of the power blockillustrated in FIG. 5.

FIGS. 8D and 8E show enlarged exploded views of parts of a fourthembodiment of power blocks of the present invention.

FIGS. 9A and 9B show perspective exploded views of components of theswingarm assembly illustrated in FIG. 5.

FIG. 10 shows a side elevation view of a drive roll of the presentinvention.

FIGS. 11A and 11B show front elevation views of first and secondembodiments of drive rolls of the present invention.

FIGS. 12A and 12B show front elevation views of portions of first andsecond embodiments of drive rolls of the present invention.

FIG. 12C shows a cross-sectional view of portions of drive rolls and awire guide of the present invention driving a weld wire.

FIGS. 13A, 13B, 13C, and 13D show top and side elevation views ofrespective embodiments of wire guides of the present invention.

FIG. 13E shows a longitudinal cross-sectional side view of the wireguide illustrated in FIG. 13A.

FIG. 14 shows a side elevation view of an inlet guide, an intermediateguide, and a liner guide of the present invention.

FIG. 15 shows an enlarged exploded view of the cover assemblyillustrated in FIG. 5.

FIG. 16 shows a cross-sectional view of parts of an embodiment of adrive assembly of the present invention with the cover in the closedposition.

FIG. 17 shows a cross-sectional view of parts of another embodiment of adrive assembly of the present invention with the cover in the closedposition.

The invention is not limited in its application to the details ofconstruction or the arrangement of the components set forth in thefollowing description or illustrated in the drawings. The invention iscapable of other embodiments or of being practiced or carried out inother various ways. Also, it is to be understood that the terminologyand phraseology employed herein is for purpose of description andillustration and should not be regarded as limiting. Like referencenumerals are used to indicate like components.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

While the present invention is illustrated with reference to aparticular welding wire feeder assembly having a particularconfiguration and particular features, the present invention is notlimited to this configuration or to these features, and otherconfigurations and features can be used.

Similarly, while the disclosure hereof is detailed and exact to enablethose skilled in the art to practice the invention, the invention isembodied in other structures in addition to the illustrated exemplarystructures. The scope of the invention is defined in the claims appendedhereto.

Referring now to FIG. 1, a welding system 10 comprises a power source12, a gas supply 14, and a wire feeder assembly 16. Preferably, powersource 12 is a constant voltage welding power source which supplieswelding arc power, and 24 VAC control power, to wire feeder 16. Wirefeeder assembly 16 is electrically connected to the power source 12 viacontrol cable 18 which carries the 24 VAC control power. Cable 18includes a control output pin 23 which engages a corresponding nut 22 onthe front panel 24 of power source 12. Also connected between powersource 12 and wire feeder assembly 16 is weld cable 26. Weld cable 26can be either a positive weld cable or a negative weld cable, dependingupon the particular welding process. Hereinafter, however, cable 26 isdescribed as a positive weld cable. As such, a negative weld cable 28also extends from the power source 12. Negative weld cable 28 extendsfrom power source 12 to a clamping member 30 which is adapted andconfigured to be attached to workpiece 32. Since positive weld cable 26extends to wire feeder assembly 16, and negative weld cable 28 extendsto workpiece 32, the requisite voltage potential between the wire feederassembly and workpiece, necessary for welding, is achieved.

Also connected to wire feeder assembly 16 is a gas hose 34 whichsupplies gas for the arc-welding process, from gas cylinder 36. Gascylinder 36 includes a regulator and flow meter 38 and, in theembodiment illustrated in FIG. 1, is securely positioned againststructure 40 via chain 42.

Wire feeder assembly 16 includes a base plate 44 which is configured tosupport wire feed spindles 46 and control box 48. On the undersurface ofbase plate 44 are a number of rubber feet 50 which help to limit slidingof wire feeder assembly 16, as is described hereinafter with respect toFIG. 2. In the Illustrated embodiment, wire feeder assembly 16 includesfirst and second welding guns 52 which are supplied with weld wire,which is initially stored on wire feed spindles 46, by correspondingdrive assembly 56. Each drive roller assembly 56 is connected to controlbox 48 by electrical leads 58.

Control box 48 includes a number of controls 60 which are used by thewelder operator in conducting the welding operation. The switches whichare indicated in controller 60 include jog/purge push buttons and anON/OFF switch (not shown). Additional controls 62 include knobs whichcontrol the wire speed and a left/right switch 64.

Referring now to FIG. 2, the aforementioned welding system can also beembodied in a portable system. That is, the wire feeder assembly 16 canbe positioned atop the power source 12 and jointly placed on a pull cart68. The previously described rubber feet 50 limit sliding movement ofthe feeder when atop the power source 12. The pull cart can also includea cylinder support tray 70 configured to support gas cylinder 36. Inthis embodiment, chain 42 is secured to plate 72 which is connected tosupport tray 70 via cross-member 74. Plate 72 is also secured to a toprear portion of power source 12. Pull cart 68 includes wheels 76 andpulling arm 78 to assist with the transportability of the weldingsystem.

Referring now to FIG. 3, in some embodiments welding system 10 comprisesa relatively stationary power source 12, and a wire feeder assembly 16,optionally at least two wire feeder assemblies 16, adapted to begenerally mobile relative to power source 12. Power source 12 can bepositioned atop frame 65, and a post 66 can extend upwardly from frame65. Beam 67 is pivotably attached to, and extends away in a firstdirection from, post 66. A support arm (not labeled) extends away frompost 66, in a second opposite direction, and holds/supports reel 53.Reel 53 is adapted and configured to hold a spindle 46 (FIG. 2) of weldwire 54 (FIG. 2).

Preferably, beam 67 comprises a vertically oriented swivel assemblywhich enables the distal end of beam 67 to pivot about the swivelassembly, upwardly away from, and downwardly toward, frame 65 along anarcuate travel path. A first wire feeder assembly 16 can be mounted tothe distal end of beam 67. In some embodiments, a second wire feederassembly 16 is mounted near the point of attachment of beam 67 to post66, and is aligned with the first wire feeder assembly 16, enabling aweld wire 54 (FIG. 2) to be fed through the first and second wire feederassemblies 16, in series.

Referring now to FIG. 4, the rear portion of wire feeder assembly 16 isshown. Control box 48 includes a back panel 80 which has a number ofcooling vents 82 and a drive assembly rotation knob 84. Also secured toback panel 80 is a pair of shielding gas valve fittings 86, each ofwhich receives a shielding gas hose. Preferably, positioned between thetwo shielding gas valve fittings 86, is a rating label 88. Control cable18 is also connected to the back panel 80 via socket 90.

Mounted adjacent each side panel 92 of the control box, and supported byplate 44, is a drive assembly 56 (FIGS. 4 and 5). Each drive assembly 56includes a motor and other related components, which are described ingreater detail below, which receive 24 VAC control power from cable 18.Also supported by base plate 44 is a pair of structures 94, eachconsisting of a vertical plate 96 and rod 98 which supports a wire spoolor reel 46 (FIG. 1). A jumper cable 100 extends between the driveassemblies, thereby providing power from the single weld cable 26 toboth drive assemblies.

One embodiment of drive assemblies 56 of the present invention is shownin exploded detail in FIG. 5. The drive assembly includes motor 102attached to a gearbox 112 which is in turn attached to isolation plate124. Also attached to isolation plate 124 is carrier plate assembly 125to which is attached swingarm assemblies 130, power block 146A (FIG. 6A)and cover assembly 160.

In some embodiments, motor 102 is e.g. a one-eighth horsepower, 24 voltDC motor. One end of motor 102 is attached to a first side of gearbox112, including a motor output shaft which is operably connected to theoperating mechanism in gearbox 112. Extending outwardly from an apertureon a second opposite side of gear box 112 is a gearbox output shaft 118.Output shaft 118 is attached to, preferably removably attached to, drivepinion 122 by conventional means of attachment, including but notlimited to, retaining rings, splined shafts and slots, keywayattachments, pins, and others. Drive pinion 122 has an outercircumferential surface which is adapted and configured to drivinglyengage the outer circumferential surface of a second pinion such ascarrier pinion 138 (FIGS. 6A and 16).

The side of gearbox 112, through which output shaft 118 extends,communicates with a first side of isolation plate 124 which isconstructed of an electrically insulating, e.g. polymeric, material. Asecond, oppositely facing side of isolation plate 124 communicates withcarrier plate assembly 125 which is attached to isolation plate 124.Gearbox 112, and thus electric motor 102, are mounted to isolation plate124, separately from carrier plate assembly 125 whereby components ofelectric motor 102 and gearbox 112 are electrically isolated fromcomponents of carrier plate assembly 125. In addition, the drive trainwhich connects shaft 118, drive pinion 122 and e.g. carrier pinions 138,includes one or more electrical isolation components which electricallyisolate the motor end of the drive train from the driven end of thedrive train. For example, drive pinion 122 can have a non-conductinge.g. nylon core which drives a conducting, e.g. metal toothed outerring, or for example a metal core which drives a non-conducting toothedouter ring. Or shaft 118 can be non-conducting, or driven pinion 138 canbe non-conducting. In light of disclosure herein, other non-conductingstructures will be known or obvious to those skilled in the art.

Power block 146A (FIG. 6A) is mounted to carrier plate 128 and is thusalso electrically isolated from components of electric motor 102 andgearbox 112. Referring again to FIG. 5, hinge pin 129 extends through atleast one aperture which extends through an upper portion of carrierplate assembly 125 and at least one aperture which extends throughswingarm assembly 130, thereby pivotably attaching swingarm assembly 130to carrier plate assembly 125.

Weld cable 26, which typically carries the welding power from powersource 12 to the drive assembly, attaches to carrier plate 128 at theend of plate 128 which is opposite power block 146A, as illustrated inFIG. 5, so as to electrically energize the drive assembly and pass thewelding power to weld wire 54.

Attached to isolation plate 124, below the point of attachment ofcarrier plate assembly 125, is cover assembly 160. Cover 164 pivotsabout pins 163 (FIG. 15), relative to isolation plate 124, between firstand second positions. In the first position, cover 164 generally coverscarrier plate assembly 125. In the second position, cover 164 generallyexposes carrier plate assembly 125. When cover 164 is in the positiongenerally covering carrier plate assembly 125, upper components of coverassembly 160 communicate with cooperating elements of swingarmassemblies 130 and apply downward forces onto the swingarm assemblies130.

Power block 146A is attached to carrier plate assembly 125. Knob 150enables a user to removably secure power pin 20 (FIGS. 6A, 6B, 6C, 6D)and thus gun 52 (FIG. 1) to power block 146A. As is described in greaterdetail below, knob 170 has an elongate projection which is threadedlyreceived in an aperture which extends through a top portion of cover164, enabling knob 170 to be manipulated by a user to adjust the amountof force which is applied to swingarm assemblies 130.

Wire guide 250 (FIG. 5) extends generally parallel to, and along aportion of, carrier plate assembly 125. Wire guide 250 is adapted andconfigured to be received between at least two of drive rolls 180 andhas first and second opposing ends. The first end of wire guide 250 isgenerally oriented toward spindles 46 (FIG. 1). The second end of wireguide 250 is generally oriented toward power pin 20.

Carrier plate assembly 125 as shown in detail in FIG. 6A includes spacerblocks 126 which communicate with isolation plate 124 (FIG. 5) andcarrier plate 128. Assembly 125 further includes carrier pinions 138which are mounted to plate 128 by bearings 139. Carrier pinions 138 arealso drivingly mounted to carriers 140 by bolt 136, which extendsaxially through the respective apertures in carrier plate 128, as wellas axially into both pinions 138 and carriers 140 such that carriers 140turn in common with pinions 138 on bearings 139.

Carrier plate assembly 125 further includes power block 146A, which ismounted to carrier plate 128, as illustrated in FIG. 6A.

Spacer blocks 126 each have a first generally planar surface facing afirst direction, which communicates with isolation plate 124 (FIG. 6A),and a second generally planar surface facing a second oppositedirection, and communicating with carrier plate 128. The distancebetween the first and second generally planar surfaces of spacer blocks126 defines a thickness dimension which is at least as great as thethickness dimension of carrier pinions 138, thus to enable carrierpinions 138 to be positioned between isolation plate 124 and carrierplate 128.

Carrier plate 128 has a plurality of apertures formed therethrough,which enable removable attachment of various components of the carrierassembly to the plate, using conventional hardware, such componentsincluding, but not being limited to, spacer blocks 126 and power block146A.

Plate 128 has a thickness dimension corresponding in general to not lessthan, typically more than, the collective thickness dimension ofbearings 139. Where, as illustrated in FIG. 6A, multiple bearings areused in side by side relationship, the thickness of plate 128 at thebearing apertures is preferably at least as great as the combinedthicknesses of all the bearings which are used in the respective bearingapertures.

The bearing apertures are sized and configured to receive the outerraces of bearings 139 to be inserted thereinto, enabling bearings 139 tobe accepted into plate 128 by e.g. a press fit. In preferredembodiments, the bearing apertures include a lip or shoulder to providea mechanical stop, and thus separation, between respective bearings 139.Accordingly, the bearings 139 are separated from each other by adistance corresponding to a thickness dimension defined by the lip orshoulder of the bearing apertures.

The thickness dimensions of spacer blocks 126 provide adequate distancebetween isolation plate 124 and plate 128 so that carrier pinions 138can generally freely rotate therebetween via bearings 139 withouttouching isolation plate 124.

A carrier pinion 138 has a generally cylindrical projection 142 which isadapted and configured to extend at least partially through, and tointerface with, an inner race of a bearing 139. The terminal end of thecylindrical projection has at least one protuberance 143 which isadapted and configured to interface with carrier 140.

A bore extends through carrier pinion 138 and its cylindricalprojection, enabling bolt 136 to extend through such bore and tothreadedly attach carrier pinion 138 and carrier 140 to each other. Body220 (FIG. 9B) of carrier 140 includes a base plate 221, which hasopposing surfaces 223A, 223B. Surface 223B has one or more receptaclesor recesses, which cooperate with and receive, protuberances 143 on thecylindrical projection of carrier pinion 138, such that the cooperationof the protuberances, and receptacles or recesses, causes carrier pinion138 to drivingly engage carrier 140, e.g. rotation of carrier pinion 138correspondingly drivingly rotates carrier 140. Carrier pinion 138 ismounted to carrier 140 by threads on bolt 136 being engaged with athreaded bore which extends through base plate 221 of carrier 140.

In some embodiments, the main power for establishing and maintaining thewelding arc is transferred from power source 12 (FIGS. 1–3) throughcable 26 (FIGS. 1 and 3) which is attached to one of the aperturesextending through plate 128. The main power for the welding arc is thentransferred through plate 128, which is made of a conductive material,through power block 146A, power pin 20, gun 52, and up to theweld/workpiece. In some embodiments, power from cable 26 is manipulated,by conventional means, to appropriate levels and thereupon is also usedto energize motor 102 as desired, whereupon cable 18 is not needed.

In some embodiments, control cable 18 electrically connects power source12 to wire feeder assembly 16, and weld cable 26 directly communicateswith and/or is attached to, welding gun 52. In such embodiments, thewelding arc power is carried from power source 12 to welding gun 52,through weld cable 26, without passing through feeder assembly 16 priorto the welding gun. Thus, in such embodiments, power pin 20 and therespective power block 146A, 146B (FIGS. 6A, 6B, 6C, 6D) do not carrywelding arc power therethrough.

Isolation plate 124, as shown in detail in FIG. 7, has a first surfacewhich faces and communicates with gearbox 112 (FIG. 5) and a secondsurface which faces the opposite direction, e.g. faces and communicateswith carrier plate assembly 125. As shown in FIG. 7, isolation plate 124has a plurality of generally annular apertures and a plurality ofgenerally elongate apertures e.g. slot-shaped openings 205, 210, 215which enable a user to adjust the mounting positions of respectivecomponents which are mounted to isolation plate 124.

Output shaft 118 and drive pinion 122 extend through opening 205,sufficiently far to enable drive pinion 122 to interface with ones ofcarrier pinions 138 (FIGS. 5 and 16). In some embodiments, gearbox 112has a generally rectangular face which communicates with isolation plate124 and the mounting structure e.g. a threaded post or bolt proximateeach corner.

Each of the mounting structures extends through respective ones of e.g.slots 210, 215, thus enabling gearbox 112 to be attached to isolationplate 124 with convention hardware. Slots 205, 210, 215 are adapted andconfigured to enable a user to mount gearbox 112 relatively higher orrelatively lower on isolation plate 124 corresponding to e.g. thediameter of a desirable drive pinion 122. Gearbox 112 is mountedrelatively lower in slots 205, 210, 215 to accommodate a relativelytaller (greater diameter) drive pinion 122 and is mounted relativelyhigher in slots 205, 210, 215 to accommodate a relatively shorter(lesser diameter) drive pinion 122.

In preferred embodiments, isolation plate 124 is made of a poorlyelectrically conducting material, e.g. electrically insulating material,so as to electrically isolate the high voltage commonly employed oncarrier plate assembly 125 and components mounted thereto, from gearbox112 and components mounted thereto. Suitable materials for makingisolation plate 124 include, but are not limited to, various polymericcompounds such as various of the polyolefins, and a variety of thepolyethylenes, e.g. high density polyethylene, or polypropylenes. Therecan also be mentioned such commodity polymers as polyvinyl chloride andchlorinated polyvinyl chloride copolymers as well as a wide variety ofthe copolymers which embody the above-recited materials, as well asothers.

Referring now to FIGS. 6A, 6B, 6C, 6D, 8A, 8B, 8C, 8D, and 8E, powerblock 146A, 146B is mounted to plate 128 at a recess in plate 128. Powerblock 146A, 146B includes knob 150, power block base 270A, 270B, and pinholder 280A, 280B. In the complete assemblage of carrier plate assembly125, power block 146A, 146B interfaces with, and/or otherwisecommunicates with, gas block 147. Gas block 147 enables the gas from gashose 34 (FIG. 1) to flow into power pin 20, and thus to welding gun 52and ultimately to the workpiece.

In some exemplary embodiments, such as those illustrated in FIGS. 6A,8A, 8B, and 8C, power block base 270A has, on one side, a concavegenerally half-cylindrical configuration, e.g. receiving structure 272A,formed therein, and on another side a convex generally half-cylindricalprojection, e.g. knuckle 274A extending upwardly therefrom. Knuckle 274Adefines an outer surface into which slot S1A extends. Slot S1Acomprehends a variety of receiving structures which include, but are notlimited to, depressions, channels, grooves, slots, apertures, and/orothers. Bore 276A extends through a medial portion of power block base270A, generally between receiving structure 272A and knuckle 274A.

Pin holder 280A has, on one side, a concave generallyhalf-cylindrical-configuration, generally continuous first reliefstructure formed therein, e.g. receiving structure 282A, and on anotherside a generally half-cylindrical-configuration second relief structure,e.g. receiving structure 284A, which is effectively discontinuous asseparated by a projection such as a rib, a protuberance, a shoulder, anoutthrust, and/or other structure that extends outwardly from thereceiving structure surface, e.g. arm 285A (FIG. 8C).

Arm 285A is shown as continuous along the length of the arm and aboutthe curved contour of the receiving structure. Discontinuous arms 285Aare also contemplated. Bore 286A extends through a medial portion of pinholder 280A generally between receiving structures 282A and 284A. Asillustrated in FIG. 8C, arm 285A is generally arcuate andextends/projects upwardly from a surface of receiving structure 284A andthus provides a generally arcuate interface adapted and configured tointerface with pin 20. In other embodiments, arm 285A is generallyplanar and extends/projects upwardly from a surface of receivingstructure 284A and thus provides a generally planar interface adaptedand configured to interface with pin 20.

In some embodiments, pin holder 280A has more than two receivingstructures formed therein. For example, pin holder 280A can furtherinclude third and fourth receiving structures (not illustrated) locatedon opposite side of bore 286A from each other and which extend indirections generally perpendicularly to the directions in whichreceiving structures 282A and 284A extend. In such alternativeembodiments, pin holder 280A as viewed from above appears generally“X-shaped” and has two pairs of generally parallel receiving structures,whereby the first and second pair of receiving structures are generallyperpendicular to each other.

Knob 150 has an elongate threaded stem which extends freely throughbores 276A and 286A, and which threadedly engages aperture 288 (FIG. 6A)in plate 128, thus mounting base 270A and pin holder 280A, andcorrespondingly power block 146A, to plate 128 while enabling pin holder280A to be rotated about the stem, as well as about base 270A.Accordingly, pin holder 280A can be rotated and/or reversed betweenfirst and second positions, optionally between other sets of positions.In the first operative position, receiving structure 272A and receivingstructure 282A are generally aligned with each other to collectivelyform a bore which has a first internally facing surface configuration,and which receives and holds pin 20. In the second operative position,receiving structure 272A and receiving structure 284A are generallyaligned with each other to collectively form a bore which has a seconddifferent internally facing surface configuration, and which receivesand holds pin 20.

Knob 150 can also be used, by way of the threaded stem, to tighten pinholder 280A against power block base 270A. Tightening knob 150, and thuspin holder 280A against power block base 270A, enables power block 146Ato securely capture and hold the power pin 20. Pin 20 can becaptured/held in the bore between receiving structures 272A and 282A,alternatively in the bore between receiving structures 272A and 284A.The determination of which set of receiving structures is used dependson the configuration of the respective power pin. In some embodiments,pin 20 has a power block interface, such as a groove or channel, whichis adapted and configured to receive arm 285A of receiving structure284A enabling arm 285A to provide a mechanical interference betweenfacing surfaces of the groove or channel of pin 20, and arm 285A ofpower block 146A, in addition to the clamping e.g. squeezing forceprovided by respective components of power block 146A.

Arm 285A can alternatively project and/or otherwise extend from othersurfaces of power block 146A and still project/extend generally into thecavity defined by the receiving structure. As one non-limiting example,arm 285A can extend from power block base 270A and into the receivingstructure cavity. As another non-limiting example, arm 285A can extendfrom both power block base 270A and pin holder 280A and into thereceiving structure cavity.

The power block interface of pin 20 and arm 285A cooperate to relativelyincrease the resistance to e.g. non-desired power pin removal, such asfor example when a user/operator does not desire pin 20 to be removedfrom power block 146A, and a force is applied generally coaxially withpin 20 in a direction outwardly from power block 146A which wouldcorrespondingly tend to urge removal of pin 20 from power block 146A.

In some embodiments, pin 20 has a generally continuous-diameterlongitudinally-extending outer perimeter, and is devoid of anystep-change power block interface and thus has, for example, a generallyconstant-magnitude outer circumferential surface. When such a pin 20,which is generally devoid of any step-change power block interface outersurface, is utilized, the user of wire feeder 16 aligns receivingstructure 284A over knuckle 274A whereupon receiving structure 282A isaligned over receiving structure 272A. This alignment of receivingstructure 284A and knuckle 274A enables arm 285A to extend into slot S1A(FIG. 8A, 8C) when, for example, the user tightens knob 150 andcorrespondingly draws pin holder 280A relatively nearer power block base270A. In this first positional configuration, the aligned receivingstructures 272A and 282A collectively define a generallycontinuous-diameter receiving structure surface e.g. a generallyconstant-diameter cylindrical bore which passes through the thusassembled combination of power block base 270A and pin holder 280A. In asecond positional configuration, receiving structures 272A and 284A aregenerally cooperatively aligned and collectively define a generallydiscontinuous-diameter receiving structure surface e.g. a receivingstructure surface which defines a receiving structure cavity, whereinarm 285A extends into the cavity.

Alternatively, at least one of receiving structures 272A, 282A, and 284Ahas, for example, a depression, groove, aperture, and/or other receivingformation formed thereinto in addition to, or in lieu of, e.g. aprojection such as arm 285A e.g. a mirror-image female representation ofarm 285A. In such embodiments, the power block interface of pin 20 has,for example, a projection extending therefrom which is adapted andconfigured to cooperate with the receiving formation of at least one ofreceiving structures 272A, 282A, and 284A. Yet other embodiments ofpower pin/receiving structure interfaces are considered including, butnot limited to, cooperating tapered interfaces, multiple projectingelements and cooperating multiple receiving elements interfaces, simplestep/shoulder interfaces, and/or others.

As one non-limiting example, at least one of receiving structures 272A,282A, and 284A further includes a channel and/or slot as a receivingformation, namely surface depression “SD”, which extends downwardly intothe inner circumferential surface of at least one of receivingstructures 272A, 282A. Surface depression “SD” is adapted and configuredto, for example, cooperate with the power block interface of pin 20.

Surface depression “SD”, as representatively illustrated in dashedoutline in FIGS. 8B and 8C has an axial channel portion and a radialchannel portion. The axial channel portion has first and second terminalends. The first terminal end of the axial channel portion communicateswith an outer edge of at least one of receiving structures 272A, 282Aand the axial channel portion extends generally axially inwardlytherefrom. The radial channel portion originates from the secondterminal end of the axial channel portion and extends generally radiallyalong at least a portion of the inner circumferential surface ofreceiving structures 272A, 282A.

Thus, surface depression “SD” enables the power block interface of pin20 to slidingly and securingly interface with power block 146A, 146B. Asone example, the power block interface of pin 20 includes a projectionextending therefrom, whereby pin 20 can be slidingly inserted into theaxial channel portion of surface depression “SD” and rotated into theradial portion of surface depression “SD.” Thus, receiving structures272A, 282A, and/or 284A define the “female” interface member and pin 20defines the “male” interface member which together cooperatinglyprovide, at least in part, a mechanical interference effective to resiste.g. non-desired power pin removal.

In some exemplary embodiments, such as those illustrated in FIGS. 6B,6C, 6D, 8D, and 8E, power block 146B includes power block base 270B andpin holder 280B which, as exemplarily illustrated, are at leastpartially integral with each other as a unitary body. Receivingstructure 272B extends axially through at least one of power block base270B and pin holder 280B and generally defines a receiving structureinner circumferential surface which in turn defines the outer perimeterof a receiving structure cavity. At least one surface depression “SD”(FIG. 8E) which is adapted and configured to, for example, cooperatewith the power block interface of pin 20, can extend into the innercircumferential surface of receiving structure 272B. A bore, namely bore286B extends through each of pin holder 280B and power block base 270B,in an orientation generally perpendicular to receiving structure 272B.

Pin holder 280B (FIG. 8D, 8E) has an upper surface which has at leastone slot, such as slot S1B and/or slot S2B which extends at least partway through the top-to-bottom thickness of the pin holder. Asexemplarily illustrated, slot S2B extends entirely through a portion ofpin holder 280B and communicates with and opens into the receivingstructure cavity of receiving structure 272B. In other embodiments, suchas the non-limiting embodiment illustrated in FIG. 6D, slot S3B extendsinto power block 146B and communicates with each of gas block 147, pinholder 280B, and the receiving structure cavity in gas block 147.

Pin holder plate 281 is adapted and configured to communicate with, andmove with respect to, other portions of pin holder 280B and otherportions of power block 146B. Pin holder plate 281 has a generallyplanar main body portion. A bore 286C, which is open, optionally notopen, along a major portion of the perimeter of the bore, extendsgenerally medially through the main body of the plate, adjacent asliding arm 285B which extends generally downwardly from the main bodyand which comprehends ribs, protuberances, shoulders, outthrusts, and/orother structures that extend outwardly from the main body of the plate.Thus, pin holder plate 281 is adapted and configured to rotatably,pivotably, slidingly, snapingly, removably, and/or otherwise movablycommunicate with e.g. the remainder of pin holder 280B.

In addition, sliding arm 285B is adapted and configured to be slidinglyinserted into and/or at least partially through at least one of slotsS1B, S2B, S3B. Accordingly, as desired, a user can selectively rotateplate 281 about the stem of knob 150, and push slide arm 285B throughthe respective slot S1B, S2B, S3B, and thus into the bore definedbetween the respective receiving structures. Or, as desired, the usercan selectively move and insert arm 285B, for example, into slot S2B,whereby sliding arm 285B generally does not extend into, protrude into,and/or otherwise communicate with, the receiving structure cavity, butnevertheless extends into a bore at or adjacent block 147, through whichpin 20 passes.

Since arm 285B has a generally planar configuration and a distal edge289 which in FIG. 8D extends in a generally straight line, arm 285Bextends into the receiving structure cavity, and provides a generallyplanar interface surface in the cavity, which generally planar interfaceis adapted and configured to interface with, to cooperate and/or tootherwise communicate with pin 20.

Distal edge 289 can alternatively extend along a generally arcuate path“AP” (illustrated in dashed outline in FIG. 8E) whereby arm 285B isadapted and configured to provide a generally arcuate interface therebyto better cooperate and communicate with the typically arcuate, e.g.cylindrical, outer surface of pin 20. Of course, arm 285B can furtherinclude other configurations such as cylindrical protrusions, serratedprotrusions, and/or others.

The integral portion of power block 146B, where base 270B and pin holder280B come together, communicates with a first radial portion 272BR ofreceiving structure 272B. The generally radially opposite side ofreceiving structure 272B communicates with an opening 287 which extendsbetween power block base 270B and pin holder 280B. Opening 287 betweenpower block base 270B and pin holder 280B enables pin holder 280B to bedrawn and/or otherwise moved relatively nearer power block base 270B,such as by flexing of the power block at or adjacent first radialportion 272BR.

Accordingly, in the complete assemblage of power block 146B, knob 150can be used, by way of the threaded stem, to draw pin holder 280B aminor distance such as 0.5–5 mm toward power block base 270A by flexingof the power block at radial portion 272BR. This provides a clampingforce sufficiently great to frictionally and/or clampingly hold powerpin 20 in power block 146B by generally constricting the power pinreceiving structure of power block 146B against at least a portion,optionally substantially all, of an outer circumferential portion of thesurface of power pin 20.

In the complete assemblage of power blocks 146A, 146B, a user can choosebetween at least first, second, and optionally more, operative relativepositions of the base 270B and the pin holder 280B based at least inpart on the particular configuration of pin 20 to be used in combinationwith wire feeder 16. In some embodiments, such as those illustrated inFIGS. 6A, 8A, 8B, and 8C, a user can loosen knob 150 and thereby alsoloosen its threaded stem, which enables pin holder 280A to move from afirst operative position, outwardly away from power block base 270A asguided by the threaded stem. When pin holder 280A is sufficientlydistanced from power block base 270A, the user can, for example,rotatably move pin holder 280A about the threaded stem by e.g. rotatingpin holder 280A by e.g. about 90 degrees of rotational travel, about 180degrees of rotational travel, about 270 degrees of rotational travel, oranother rotational travel distance as appropriate to the structure ofthe respective power block, and the respective pin holder.

The user can then tighten knob 150 and its threaded stem so as to securepin holder 280A against power block base 270A in a second operativeposition. Thus, it is contemplated that in the first operative positionreceiving structure 282A is generally operatively aligned with receivingstructure 272A whereby the receiving structure has a generally constantdiameter bore as a receiving surface e.g. the bore is devoid of arm285A. In the second operative position, receiving structure 284A isgenerally operatively aligned with receiving structure 272A and arm 285Agenerally extends into the receiving structure cavity whereby thediameter of the bore of the receiving structure cavity comprehends atleast one step change.

Referring specifically to the embodiments of FIGS. 6B, 6C, 6D, 8D, and8E, a user can loosen knob 150 and thereby also loosen its threadedstem, which enables pin holder plate 281 to be moved from a firstoperative position, outwardly away from pin holder 280B as guided, atleast in part, by the threaded stem. When pin holder plate 281 issufficiently distanced from pin holder 280B, the user can, for example,rotate the pin holder plate 281 about the threaded stem by e.g. rotatingpin holder plate 281 by e.g. about 90 degrees of rotational travel,about 180 degree of rotational travel, about 270 degrees of rotationaltravel, or another rotational travel distance. When pin holder plate 281is movably free, the user can insert arm 285B into a desired one of, forexample, slots S1B, S2B, S3B.

The user can then tighten knob 150 and its threaded stem so as to securepin holder plate 281 against pin holder 280B in a second operativeposition, e.g. between knob 150 and the outer surface of pin holder280B, optionally a third operative position, and optionally otheroperative positions. As one example, it is contemplated that the firstoperative arm 285B is inserted into slot S2B (FIG. 6C) or S3B (FIG. 6D)and extends at least partially into and/or otherwise communicates withthe receiving structure cavity. In the second operative position, arm285B is inserted into slot S1B (FIG. 6B) and generally does not extendinto the receiving structure cavity.

Accordingly and as desired, the user can change the surfacecharacteristics of the receiving structure by, for example, changing theorientation of one or more components of power block 146A, 146B withrespect to other components of power block 146A, 146B. Namely, the usercan move pin holder 280A and/or pin holder plate 281 as desired toprovide the receiving structure with, for example, a generallylongitudinally constant diameter inner circumferential surface or agenerally longitudinally changing-diameter inner circumferential surfacebased at least in part on the particular configuration of the particularpin 20 which is being utilized.

Referring now to FIG. 9A, each swingarm assembly 130 includes a swingarm132, one of the carrier pinions 138, first and second bearings 139, anda carrier 140. A bore 292 extends through swingarm 132, the bore beingsized and configured to receive the outer races of bearings 139, thusenabling the bearings 139 to be accepted into swingarm 132 by a pressfit. In preferred embodiments, bore 292 includes a lip or shoulder toprovide a mechanical stop, and thus separation, between respectivebearings 139. Accordingly, the bearings 139 are separated from eachother by a distance corresponding to a thickness dimension defined bythe lip or shoulder of the bore 292.

Bolt 136 extends through the bore of carrier pinion 138 and terminatesin carrier 140, generally attaching the two. As described above, carrierpinion 138 has one or more protuberances 143, and carrier 140 hascorresponding interfacing receptacle structure which enables the carrierpinion 138 to be drivingly coupled to carrier 140, thus to drivinglyengage carrier 140.

Swingarm assembly 130 is pivotably attached to carrier plate assembly125 by hinge pin 129 (FIG. 5), thus enabling swingarm assembly 130 topivot between a first generally open position, as suggested by FIG. 5and a second generally closed position (FIG. 16). In the generallyclosed position, the upper carrier pinion 138, which is mounted toswingarm 132, is engaged by the corresponding lower carrier pinion 138,which is mounted to carrier plate 128 and which is driven by drivepinion 122. Thus, with the swingarm assembly positioned in the closedposition, rotation of drive pinion 122 causes corresponding driving androtation, in cooperative unison, of the upper and lower carrier pinions,and corresponding rotation of the respective drive rolls 180, which aremounted to the carriers 140, which are mounted to the respective carrierpinions 138.

Thus, the outer circumferential surface of an upper carrier pinion 138,which is mounted to swingarm 132, is adapted and configured to interfacewith a respective outer circumferential surface of a corresponding lowercarrier pinion 138, such as by corresponding meshing teeth on respectiveones of upper and lower carrier pinions 138, enabling drive pinion 122(FIG. 5) to drive a lower carrier pinion 138 on plate 128 (FIG. 6A)which, in turn, drives the respective upper carrier pinion 138 on arespective swingarm 132.

Carrier 140 as shown in detail in FIG. 9B includes, in general, body 220and button 230. Body 220 includes base plate 221, and open-facedreceptacle 224 extending away from surface 223A of the base plate. Slots222 extend through the side wall of receptacle 224. Receptacle 224 andbase plate 221 collectively define an inner cavity 226. Interface lugs228 extend outwardly of the outer surface of the side wall of receptacle224, and the open end of receptacle 224 is sized and configured toreceive button 230 into inner cavity 226.

Compression spring 225 is received into cavity 226, and extends betweenbase plate 221 and button 230, and biases button 230 away from baseplate 221. Groove 232 is an annular depression formed in the innercircumferential surface of the side wall of button 230. Apertures 233extend through the side wall of button 230 at groove 232, and are sizedand configured to confiningly pass ball bearings 237 therethrough.

Compression ring 235 is adapted and configured to be biasingly held ingroove 232 and to apply a biasing, outwardly-directed force against ballbearings 237.

Each of slots 222 in the sidewall of receptacle 224 defines an openingwidth dimension between the elongate side walls of each respective slot.Each ball bearing 237 has a diameter of greater magnitude than themagnitude of the width of the respective slot 222 into which the ballbearing is mounted, which prevents the respective ball bearing 237 frompassing through the corresponding slot 222. Accordingly, the ballbearing 237 extends freely through the respective apertures 233, asbiased by compression ring 235, and partially through the respectiveslot 222 but is prevented, by the limited width of slot 222, frompassing entirely through the respective slot 222, thereby to hold arespective drive roll 180 onto carrier 140, as explained in more detailfollowing.

Referring now to FIGS. 10, 11A, 11B, 12A, 12B, and 12C, a drive roll 180has a circular outer periphery 182 and a concentric bore 240, a firstside 238, and a second side 239. Drive roll 180 has a generallycircumferential outer body surface 290 wherein the magnitude of thecircumference of the outer diameter varies on a traverse between thefirst and second sides of the drive roll. First and second elevated wireinterfaces 244 extend annularly outwardly from lesser diameter base bodysurface portions of outer body surface 290. In some embodiments, groove294 of the elevated wire interface 244 expresses an arcuate, e.g.semi-circular, cross-section (FIG. 12A). Such arcuate shape enablesgroove 294 to generally interface with the entirety of the lower portionof the surface of weld wire 54.

In other embodiments, the groove expresses an angular cross-section,optionally a V-shaped cross-section (FIG. 12B), whereby groove 294generally supports/drives at two opposing contact points on the surfaceof weld wire 54, the opposing contact points being below the center-lineof, and above the bottom-most surface of, weld wire 54. Typical openingcross-sections for both semi-circular and angular shaped grooves 294include, but are not limited to, cross-sections which receive weld wire54 having diameter of 0.03 inch, 0.035 inch, and 0.045 inch.

Preferably, each of two grooves 294 is located at a common distance D(FIG. 11A) from sides 238 and 239, respectively.

Referring to FIG. 10, three circumferentially spaced through-slots 242extend between the first and second sides 238 and 239 of the drive roll.Each through slot 242 opens into concentric bore 240 and is sized andconfigured to receive a lug 228 of carrier body 220, whereby drive roll180 is slidingly received onto carrier 140 (FIG. 9).

Circumferential outer body surface 290 of a drive roll 180 defines abase body surface BBS at dimension BD (FIGS. 11A and 11B), which basebody surface supports the wire interface structure. The base bodysurface BBS need not be circular, and can have any of a wide range ofsurface configurations about the periphery of the drive roll.

Elevated wire interface 244 defines an interface diameter DAG at thecircumferential tops, peaks, of grooves 294. In the illustratedembodiments, each wire interface structure 244 has first and secondpeaks, spaced laterally from each other, and a groove 294 therebetween;and the cross-section of the groove corresponds in general, including inmagnitude, to the outer surface of the weld wire. In the arcuateembodiments of the grooves, the arc of the groove follows the arc of thewire quite closely. In the more angular, e.g. V-shaped grooves, thegroove corresponds with the wire size, but deviates from the outlinedefined by the outer surface of the wire. Rim 246 defines a rim diameterRD at the top of rim 246.

Referring to FIG. 12A, the lowest point of groove 294 is displacedoutwardly from base body surface BBS by a distance D2. The outer-mostportion of elevated wire interface 244, namely the top of groove 294, isdisplaced outwardly from base body surface BBS by a distance D3. Theouter-most portion of rim 246, namely the top of rim 246, is displacedoutwardly from base body surface BBS by a distance D4 (FIG. 12B). Insome embodiments, the magnitude of distance D4 is greater than themagnitude of distance D3 whereby external forces directed generally atthe outer body surface of the drive roll tend to impact at rims 246 inpreference to grooves 294. Thus, the even slight elevation of rim 246above the height of the tops of grooves 294 (greater diameter) operatessuch that rims 246 serve in a protective role with respect to grooves294. For instance, if the drive roll is dropped onto a flat surface suchas a floor, the impact is typically received at one of rims 246, wherebythe grooves 294 are unaffected by such minor accidents.

Referring now to FIGS. 13A, 13B, 13C, 13D, and 13E, wire guide 250 hasan elongate body which extends between first and second ends 296A, 296Brespectively. A cylindrical end counter bore 257 extends from the firstend axially and longitudinally into the elongate body of guide 250.Conical end counter bore 259 extends from the second, opposite endaxially and longitudinally into the elongate body. Main bore 255 has adiameter which corresponds closely to the diameter of a weld wire 54 tobe fed through bore 255, and extends generally the full length of guide250 between cylindrical end bore 257 and conical end bore 259, generallycentrally through the elongate body of guide 250 so as to providelateral support to the weld wire for substantially the full length ofthe path of travel of the weld wire through drive assembly 56. Asillustrated in FIG. 16, where bore 265 does not provide lateral supportfor the full circumference of the wire, namely the bore provides supportonly on the sides of the wire, the wire is otherwise supported on thetop and bottom by the upper and lower drive rolls 180.

Cylindrical end bore 257 is adapted and configured to accept liner 19 ofa welding gun 52. Conical bore 259 is adapted and configured to acceptinlet guide 17 where the welding wire feeds into the drive assembly.Inlet guide 17 and liner 19 each have through bores sized to correspondto the weld wire 54 of the size for which the wire guide is designed andconfigured, whereby inlet guide 17, liner 19, and wire guide 250 allhave generally common-size through bores which are adapted andconfigured to collectively provide for columnar support of the weld wireas the weld wire traverses the drive assembly.

The interfacing of liner 19 and counter bore 257 provides positionalalignment and support and stabilization to guide 250 at first end 296A.Guide 250 is additionally aligned and/or supported and stabilized byinlet guide 17 at second end 296B.

Guide 17 is held in a relatively fixed position by the interface ofo-ring 21 and a support structure, e.g. inlet guide block 311 (FIG. 17),which has an annular cavity which extends generally parallel to carrierplate assembly 125 and in line with the desired path of advance of wire54 (FIG. 5). The annular cavity extending into inlet guide block 311includes a lip or shoulder to provide a mechanical stop, whichlongitudinally holds guide 17. In alternative embodiments, wire guide250 is generally held and positioned, in the drive assembly, only bycorresponding ones of drive rolls 180 above and below wire guide 250.

Inlet guide 17 can be a separate element, an end of which is mountedinto wire guide 250. In the alternative, inlet guide 17 can be anintegral part of the wire guide, e.g. integrally molded as part of, orotherwise attached to, wire guide 250 whereupon O-ring 21 cancommunicate directly with the outer surface of the elongate body of wireguide 250, via a channel in the elongate body. Where the collar is aseparate element, such O-ring channel is part of the separate collarelement. In any event, inlet guide 17 includes a collar 295 whichextends outwardly of the outer surface of the elongate body of wireguide 250, away from the longitudinal axis of the wire guide, at oradjacent the inlet end of the elongate body. O-ring 21 is received intoa circumferentially-extending recess configured in the outer surface ofinlet guide 17, e.g. a recess in the collar.

In the process of assembling the wire guide 250 to the drive assembly,the user inserts a portion of liner 19, extending from power pin 20,into cylindrical end counter bore 257 and inserts a conically taperedend of inlet guide 17 into conical end counter bore 259 which generallycoaxially aligns (i) bore 255, (ii) a bore extending through liner 19,and (iii) a bore extending through inlet guide 17, with each other;thereby enabling weld wire 54 to pass through inlet guide 17, wire guide250, and liner 19, in succession toward the welding arc, without passingthough any substantial distance wherein the welding wire is unsupportedalong its sides. Namely, at virtually all locations between inlet guide17 and liner 19, the wire columnar strength is supported by either bore255, or guide 17, or liner 19, or grooves 294 of the drive rolls.

Referring to FIGS. 13C and 13E, first and second diametrically opposeddepressions, e.g. upper depression 260 and lower depression 262, extendinwardly from relatively top and bottom surfaces of the wire guidetoward bore 255, and open into opposing sides of bore 255. Theintersection of upper depression 260, lower depression 262, and bore 255defines aperture 265 (FIGS. 13B, 13D) which extends through guide 250from top to bottom. Typically, the width of aperture 265, across thewidth of the guide, is no more than three times, preferably no more thantwo times, the diameter of bore 255, and may be as small assubstantially equal to the diameter of the bore, or any size between thediameter of the bore and three times the diameter of the bore. In someembodiments, wire guide 250 has a single pair of diametrically opposeddepressions (FIG. 13C). In other embodiments, wire guide 250 hasmultiple pairs of diametrically opposed depressions (FIG. 13E).

As illustrated in e.g. FIG. 12C, the contours and radii of upperdepression 260 and lower depression 262 correspond generally to outercircumferential surface characteristics, namely outer body surface 290,of corresponding drive rolls 180 which interface with the respectivedepressions. In some embodiments, the thickness dimension of drive roll180, defined by the distance between drive roll sides 238 and 239, isgreater than the maximum thickness dimension of wire guide 250 betweensides 298A and 298B (FIG. 13B).

Upper depression 260 and lower depression 262 can have differingcontours and radii, such as when the drive roll 180 communicating withupper depression 260 and the drive roll 180 communicating with lowerdepression 262 have differing e.g. surface characteristics. Accordingly,wire guide 250 can have dissimilar upper depressions 260 and lowerdepressions 262 while still providing material between respective outercircumferential surfaces of corresponding ones of drive rolls 180, suchas for example when at least one drive roll 180 has at least one channeladapted and configured to allow for guide material clearance.

In alternative embodiments, weld wire 54 is supported and or guided by aplurality of weld wire guides (FIG. 17), e.g. inlet guide 17,intermediate guide 317, and liner guide 318, each of which communicateswith the outer circumferential surface of a drive roll 180. A boreextends through each of inlet guide 17, intermediate guide 317, andliner guide 318, respective ones of such bores being generally coaxialto other ones of such bores. Inlet guide 17, intermediate guide 317, andliner guide 318, are respectively housed in inlet guide block 311,intermediate guide block 312, and liner guide block 313, each of whichare in turn mounted to carrier plate 128.

A bore extends through each of inlet guide block 311, intermediate guideblock 312, and liner guide block 313. An annular cavity extends intoeach of inlet guide block 311, intermediate guide block 312, and linerguide block 313, generally concentric with each respective bore, andbeing generally parallel to carrier plate assembly 125 and in line withthe desired path of advance of wire 54 (FIG. 5). In preferredembodiments, the annular cavity extending into each of inlet guide block311, intermediate guide block 312, and liner guide block 313 includes alip or shoulder adjacent the intersection of the annular cavity and thebore, providing a mechanical stop which longitudinally holds guiderespective ones of inlet guide 17, intermediate guide 317, and linerguide 318.

In preferred embodiments, a longitudinally outwardly facing surface ofeach of collars 295, 320, and 325 (FIG. 14) interfaces with the lip orshoulder in the annular cavity of respective ones of inlet guide block311, intermediate guide block 312, and liner guide block 313,correspondingly longitudinally holding respective ones of inlet guide17, intermediate guide 317, and liner guide 318.

Intermediate guide 317 (FIGS. 14, and 17) has a first tapered end 322Adisposed toward inlet guide 17 and a second tapered end 322B disposedtoward power pin 20. Each of first and second tapered ends 322A, 322Bhas a generally arcuate profile. The contours and radii of the generallyarcuate profiles of each of first and second tapered ends 322A, 322Bcorrespond generally to outer circumferential surface characteristics,namely outer body surface 290, of corresponding drive rolls 180 whichinterface with the generally arcuate profiles.

Collar 320 extends outwardly of the outer surface of intermediate guide317, away from the longitudinal axis of the intermediate guide, betweenthe first and seconds ends 322A, 322B. O-ring 21 is received into acircumferentially-extending recess configured in the outer surface ofintermediate guide 317, e.g. a recess in the collar.

Liner guide 318 has a first, tapered end 332 disposed toward liner 17,and a second end which has a generally circular face and a generallyplanar profile. A cylindrical end counter bore 257 extends from thesecond end axially and longitudinally into the liner guide 318.Cylindrical end bore 257 is adapted and configured to accept liner 19 ofa welding gun 52.

The first, tapered end 332 of liner guide 318 has a generally arcuateprofile. The contours and radii of the generally arcuate profiles oftapered end 332 corresponds generally to the outer circumferentialsurface characteristics, namely outer body surface 290, of correspondingdrive rolls 180 which interface with the respective generally arcuateprofile.

Collar 320 extends outwardly of the outer surface of liner guide 318,away from the longitudinal axis of the liner guide, between the firstand seconds ends. O-ring 21 is received into acircumferentially-extending recess configured in the outer surface ofliner guide 318, e.g. a recess in the collar.

Referring now to FIG. 15, cover assembly 160 generally covers theinternal working components of drive assembly 56. Cover assembly 160generally includes the cover main body 164, lower bracket 161, pressurearm 168, and knob 170. Cover main body 164 includes upwardly extendingside panel 165, a lower flange 167, and upper flange 166.

Lower bracket 161 is mounted to isolation plate 124 (FIG. 5) and hasfirst and second apertures 297 on opposing ends of the bracket, axiallyaligned with each other. Hinge lobes 162 are located at the lower end oflower flange 167 and have apertures 301 which are axially aligned witheach other and with apertures 297 in bracket 161. Pivot pins 163 extendthrough apertures 297 and 301, pivotably mounting cover 164 to bracket161, and thus pivotably mounting cover 164 to isolation plate 124.

Upper flange 166 extends outwardly from side panel 165 and has first andsecond seats 300 (FIG. 15). Each seat comprises a relatively largerdiameter blind bore into the top surface of the upper flange, and arelatively smaller diameter and concentric through-bore. Pressure arm168 generally extends along a major portion of upper flange 166 infacing but spaced relationship with upper flange 166. First and secondblind bores (not shown) extend upwardly from the lower surface of thepressure arm.

Each of the blind bores in the pressure arm receives a first terminalend of a compression spring 172. A second opposite end of thecompression spring extends over and generally engages a pressure foot176, holding the pressure foot against the bottom of the blind bore ofthe respective seat. Each pressure foot 176 has a projection whichextends through the upper flange at the through bore and interfaces withthe respective underlying swingarm 132 when cover assembly 160 is closedover the internal working elements of drive assembly 56.

The loading force of springs 172 transfers, through the projection ofpressure feet 176, to the underlying swingarms 132, from the swingarms132 to the upper drive rolls 180, and from the upper drive rolls to andthrough wire 54 to the lower drive rolls, thus pinching weld wire 54between corresponding ones of the drive rolls 180 which are mounted onswingarms 132 and plate 128 respectively, above and below the respectivelength of the wire 54 which is engaged by the drive rolls.

Knob 170 of the cover assembly (FIG. 15) has a threaded elongateprojection, e.g. a stem 304, which extends through a bore 306 in amedial section of pressure arm 168 and a bore 308 in a medial section ofupper flange 166. The threaded stem of knob 170 is captured by athreaded nut 171 which is fixedly secured to upper flange 166. As analternative, the stem can be captured by threads in the bore of upperflange 166. Adjusting the relative tightness of knob 170, e.g. rotatingknob 170, correspondingly adjusts the relative load that springs 172apply to pressure feet 176.

Springs 172 can have pre-selected spring constants and/or tensions whichcorrespond relatively closely to the desired loading force to be appliedto pressure feet 176 e.g. spring loading force, thereby reducing theamount of adjusting of the relative tightness of knob 170 to achieve thedesired loading force to be applied by springs 172 to pressure feet 176.Alternatively, the spring constants and/or tensions can be pre-selectedclosely enough to the desired loading force to generally eliminate theneed for adjusting the relative tightness of knob 170 and therebygenerally reducing, alternatively eliminating, the need for knob 170. Insuch scenario, spring tension can be adjusted by replacing springs 172with springs having different spring constants and/or tensions, e.g.relative greater spring tensions or relatively lesser spring tensions,as desired.

A drive assembly 56 of the present invention, with cover 164 closed overe.g. drive rolls 180, is shown in cross-sectional view in FIG. 16.Referring to FIGS. 13E and 16, corresponding pairs of drive rolls 180interface with upper depression 260 and lower depression 262,respectively, of wire guide 250 and communicate with each otherindividually at apertures 265, through their collective grip on weldwire 54. Drive rolls 180 can further communicate with each otherdirectly, at laterally displaced, facing ones of rims 246 when no wire54 is present in groove 294. Thus, where a weld wire 54 is disposed in agroove 294, the pressure imposed by springs 172 passes through swingarm132 such that the groove 294 in the upper drive roll 180, on theswingarm, presses against the weld wire, through aperture 265, thusapplying sufficient force between the upper and lower drive rolls 180that the driving force, applied by the rotationally-driven lower driverolls, is effective to drive the weld wire 54 through the driveassembly, through liner 19 and to the contact tip of a gun 52. In suchscenario, the lower drive roll is acting on the weld wire 54 through thesame aperture 265.

Where no wire is present in a groove 294, and where the distance D4 isgreater than the distance D3, the force of spring 172 brings the rim(s)246 of an upper drive roll into contact with the corresponding rim(s) ofa respective lower drive roll, such that the downward movement ofswingarm 132 is stopped by the cooperating rims 246 before there is anycontact between the grooves 294 in the upper and lower rolls. By thusavoiding contact between the grooves, even when no wire 54 is present,such as when the wire on a spindle 46 has run out, any potential damageto e.g. the upper edges of such grooves, top of the groove, which mightoccur as a result of such contact, is avoided. Here, again, rims 246operate in a protective role to protect grooves 294 from inadvertente.g. damage or deformation beyond the ordinary wear and tear of drivingthe weld wire. Rims 246 can have a planar outer surface, as illustratedin the drawings, where facing rims meet each other. In the alternative,the meeting outer surfaces of the rims can be arcuate, such that, ineither case, the rims do not contact each other with sharp points whichcould damage either or both of the rims.

The base body surface BBS can be designed with multiple radii dimensionsat the bottoms of the respective e.g. three channels 302 between grooves294, and between grooves 294 and rims 246 (FIGS. 12B and 12C). FIG. 12Cillustrates the interfacial cooperation between the side walls ofchannels 302 and corresponding side walls of apertures 265. As seentherein, side walls of aperture 265 are in close proximity, and arelaterally adjacent the side walls of channels 302. Thus, the side wallsof the channels prevent substantial lateral movement of the wire guideat the drive rolls, whereby the drive rolls stabilize the wire guideagainst lateral movement with respect to the drive rolls. While thedrive rolls are thus configured to interface with the wire guide 250,the relative dimensions of the wire guide and the drive rolls are suchthat the wire guide is loosely held in place, so as to provide clearancebetween the drive rolls and respective portions of wire guide 250 e.g.ridges 299, without incurring so much friction between the wire guideand the drive rolls as to cause binding of the wire guide relative tothe drive rolls.

As with the dimensions BD and DAG, when the base body surfacecomprehends multiple radii dimensions, channel to channel, thedimensions D2, D3, and D4 are then preferably measured either asdiameters, or as radii from the axis of rotation 310 of drive roll 180,rather than from the base body surface at a respective channel 302.

In ordinary use of cover assembly 160, the user rotates knob 170, thusadvancing the knob into the holding threads, and thereby moving pressurearm 168 toward flange 166, which increases the load that springs 172apply through pressure feet 176 and swingarms 132, thereby increasingthe pinching force that drive rolls 180 apply to weld wire 54. The usercan rotate knob 170 in the opposite direction, thus to enable springs172 to push pressure arm 168 respectively further away from flange 166,thereby decreasing the spring force being applied, and correspondinglydecreasing the load that springs 172 apply through pressure feet 176 andswingarms 132, which decreases the pinching force that drive rolls 180apply to weld wire 54.

Drive assemblies 56 of the invention are used by first determining whichweld wire 54 is suitable for the welding application and subsequentlyselecting suitable drive rolls 180 which have e.g. grooves 294 which arecompatible with the weld wire.

As desired, a user can change/replace drive rolls 180 to correspond withthe current welding task. First, the user selects suitable drive rollsbased, at least in part, on the type and/or size of weld wire 54 to beused in the welding process.

In an assembly wherein a drive roll 180 is assembled to e.g. a swingarm132, or to plate 128, one of the sides 238, 239 of the drive roll isproximate, and in facing relationship with, surface 223A of base plate221 of body 220, which is part of carrier 140. In such assembly, spring225 is urging button 230 away from base plate 221 of body 220. At thesame time, compression ring 235 is urging ball bearings 237 outwardlythrough apertures 233 and into confining slots 222. Accordingly, spring225 pushes the button, and thus ball bearings, away from the base platewhile compression ring 235 pushes the ball bearings into slots 222.Under that set of forces, the force of spring 225 moves button 230outwardly, away from base plate 221, until the ball bearings reach thedistal ends of slots 222, whereupon the abutment of ball bearingsagainst the ends of the slots prevents further outwards movement of thebutton, whereby assembly of the drive roll of swingarm 132 or plate 128is complete.

The distal ends of slots 222 are so positioned, relative to base plate221, that in the fully assembled condition, wherein ball bearings 237are abutting the distal ends of slots 222, the ball bearings 237 arepositioned generally further away from base plate 221 than therespective distal side 238, 239 of the drive roll. Specifically, arespective ball bearing is abutting the distal slot end, relative tobase plate 221, and is in engaging contact with, and extends a bit over,the respective side 238, 239 of the drive roll, at bore 240. Suchrelationships, wherein the drive roll is assembled to carrier 140, areillustrated in FIGS. 9 and 16.

Thus, ball bearings 237 serve both to limit and/or stop the outwardmovement of button 230 at the end of slot 222, and to hold the driveroll firmly mounted to the respective swingarm 132 on plate 128 byabutting the side 238, 239 of the drive roll. Meantime, lugs 228 on thebody are received in slots 242 on the drive roll, whereby rotation ofcarrier 140 by the respective carrier pinion 138 causes rotation of therespective drive roll 180, thus to drive weld wire 54 when the coverassembly 160 is closed on the drive assembly.

To remove a drive roll from the drive assembly, the user presses button230 firmly inwardly into body 220 against the collective resistingforces of spring 225 and compression spring/ring 235, plus the initialresistance imposed by ball bearings 237. Such movement of button 230requires retraction of the extension of the ball bearings 237 over thesides 238, 239 of the drive roll. Namely, the force exerted by button230 on the ball bearings at apertures 233 applies forces, at thecontacts of the bearings with bore 240 of the drive roll, which forcethe bearings to move in an inward direction into the button, against theoutwardly-directed force of compression ring 235. Such movement of thebearings brings the bearings 237 completely inside bore 240 such thatthe drive roll is released from the immobilizing force of the bearingson the drive roll. However, the force of compression ring 235 stillpushes bearings 237 outwardly against the inner surface of bore 240.

Once the bearings are thus fully retracted, and are pressing against theinner surface of the bore, the outwardly-directed force of the bearingsbrings the bearings into modest frictional engagement with the innersurface of bore 240. Thus, any movement of the bearings along the lineof direction of movement of the button 230 applies a correspondingmodest force, in the same direction to the drive roll.

As the button is pushed inwardly, toward base plate 221, the drive rollcannot move because of being adjacent base plate 221. However, oncebutton 230 is released, and begins moving back away from base plate 221,under the restorative force of spring 225, compression ring 235continues to bias ball bearings 237 against the inner surface of bore240. The frictional forces between ball bearings 237 and the innersurface of bore 240 are sufficiently great that drive roll 180 iscarried outwardly away from base plate 221 with button 230, whereuponthe drive roll is delivered for facile removal removed from carrier 140.

Thus, pressing and releasing button 230 both releases the drive roll,and moves the drive roll outwardly on carrier 140, for facile removal bythe user.

To install a suitable drive roll 180, the user aligns through slots 242of a drive roll 180 with corresponding lugs 228 of a carrier 140. Theuser then pushes the drive roll onto the carrier. As the drive roll ispushed onto the carrier body 220, the respective side 238, 239, at bore240 pushes against the ball bearings 237 in slots 222, thus pushing theball bearings toward base plate 221, carrying button 230 along. When theproximal edge of button 230 abuts 221, the button stops moving. Uponfurther pushing of the drive roll toward base plate 221, the respectiveside 238, 239 of the drive roll, at bore 240, pushes the ball bearingsinwardly against compression ring 235, whereupon the drive roll advancesinto close proximity to surface 223A of the base plate, while bearings237 are pressed against the inner surface of bore 240 by compressionspring/ring 235.

In that condition, the retractive force of spring 225 is sufficient tomove the button, and ball bearings 237 with it, away from base plate221, whereby ball bearings 237 move outward along slots 222 until thebearings abut the distal ends of the slots. In that condition, thebearings are disposed generally outwardly of the drive roll, asindicated above, and also extend a bit over the respective sides of thedrive roll, thereby capturing the drive roll between the bearings andthe base plate.

The user then adjusts drive roll pressure by turning, e.g. tightening orloosening knob 170. Preferably, the user adjusts drive roll pressure toa pressure level which applies sufficient pressure to drive weld wire 54through the wire feeder assembly 16 without undesired levels of wireslippage, while not applying so much pressure that drive rolls 180unnecessarily deform weld wire 54.

Preferably, drive assembly 56 is made of materials which resistcorrosion, and are suitably strong and durable for normal extended use.Those skilled in the art are well aware of certain metallic andnon-metallic materials which possess such desirable qualities, andappropriate methods of forming such materials.

Appropriate metallic materials for components of drive assembly 56include, but are not limited to, aluminum, steel, stainless steel,titanium, magnesium, brass, and their respective alloys. Common industrymethods of forming such metallic materials include casting, forging,shearing, bending, machining, riveting, welding, powdered metalprocessing, extruding and others.

Non-metallic materials suitable for components of drive assembly 56,e.g. inlet guide 17, isolation plate 124, spacer blocks 126, parts ofknobs 150 and 170, wire guide 250, and others, are various polymericcompounds, such as for example and without limitation, various of thepolyolefins, such as a variety of the polyethylenes, e.g. high densitypolyethylene, or polypropylenes. There can also be mentioned as examplessuch polymers as polyvinyl chloride and chlorinated polyvinyl chloridecopolymers, various of the polyamides, polycarbonates, and others.

For any polymeric material employed in structures of the invention, anyconventional additive package can be included such as, for example andwithout limitation, slip agents, anti-block agents, release agents,anti-oxidants, fillers, and plasticizers, to control e.g. processing ofthe polymeric material as well as to stabilize and/or otherwise controlthe properties of the finished processed product, also to controlhardness, bending resistance, and the like.

Common industry methods of forming such polymeric compounds will sufficeto form non-metallic components of drive assembly 56. Exemplary, but notlimiting, of such processes are the various commonly-known plasticsconverting processes.

Drive assembly 56 is preferably manufactured as individual components,and the individual components assembled as sub-assemblies, including butnot limited to motor 102 and components attached thereto e.g. gearbox112, drive pinion 122, and isolation plate 124; carrier plate assembly125; swingarm assemblies 130; and cover assembly 160. Each of theaforementioned sub-assemblies is then assembled to respective other onesof the sub-assemblies to develop drive assembly 56. Those skilled in theart are well aware of certain joinder technologies and hardware suitablefor the assembly of drive assembly 56.

Finally, in preferred embodiments, the modularity of drive assembly 56,and the structure of each of its components, facilitate manufacture,service and repair of the drive assembly. In preferred embodiments,isolation plate 124, carrier assembly 125, swingarm assemblies 130, andcover assembly 160 are symmetrical, making them suitable forinstallation as components of drive assembly 56 whether mounted to, e.g.either a left or a right side of control box 48 (FIG. 1).

Those skilled in the art will now see that certain modifications can bemade to the apparatus and methods herein disclosed with respect to theillustrated embodiments, without departing from the spirit of theinstant invention. And while the invention has been described above withrespect to the preferred embodiments, it will be understood that theinvention is adapted to numerous rearrangements, modifications, andalterations, and all such arrangements, modifications, and alterationsare intended to be within the scope of the appended claims.

To the extent the following claims use means plus function language, itis not meant to include there, or in the instant specification, anythingnot structurally equivalent to what is shown in the embodimentsdisclosed in the specification.

1. A welding gun power block for holding a welding gun power pin, saidpower block comprising: (a) a welding gun power block base; (b) awelding gun power pin holder; said power block base and said power pinholder collectively defining a bore extending through said power block,and (c) a sliding arm movable between at least a first position and asecond position said sliding arm, in the first position extending atleast partially into said bore and said sliding arm in the secondposition, generally not extending into said bore.
 2. A welding gun powerblock as in claim 1 wherein said sliding arm extends from said power pinholder.
 3. A welding power block as in claim 1 wherein said sliding armextends from said power block base.
 4. A welding gun power block as inclaim 1 wherein said sliding arm defines a generally planar interfacesurface adapted and configured to interface with such welding gun powerpin.
 5. A welding gun power block as in claim 1 wherein said sliding armdefines a generally arcuate interface surface adapted and configured tointerface with such welding gun power pin.
 6. A welding gun power blockas in claim 1 wherein said sliding arm is rotatably movable between atleast a first position and a second position.
 7. A welding systemcomprising a wire feeder apparatus having a power block as in claim 1.8. A welding gun power block for holding a welding gun power pin, saidwelding gun power block comprising: (a) a welding gun power block base;and (b) a power pin holder mounted to said power block base, andpivotably movable between at least a first position and a seconddifferent position; said power block base and said power pin holdercollectively defining a bore extending through said power block, saidbore having an inwardly-facing bore surface, wherein, when said powerpin is in said first position, a respective inwardly-facing bore surfaceextends axially of the bore along a generally smooth and continuous pathof advance, and when said power pin holder is in said second position,the respective inwardly-facing bore surface extends axially of the borealong a path containing at least one step discontinuity in pathdirection.
 9. A welding gun power block as in claim 8 wherein said powerpin holder is rotatably movable between at least a first position and asecond position.
 10. A welding gun power block as in claim 8 whereinsaid power pin holder comprises a power pin holder plate which ismovable between at least a first position and a second position.
 11. Awelding gun power block as in claim 10 wherein said power pin holderplate is rotatably movable between at least a first position and asecond position.
 12. A welding system comprising a wire feeder apparatushaving a welding gun power block as in claim
 8. 13. A welding gun powerblock for holding a welding gun power pin, said welding gun power blockcomprising: (a) a power block base having a first receiving structureextending thereinto; and (b) a power pin holder having a secondreceiving structure extending thereinto; said power block base and saidpower pin holder collectively defining a bore extending through saidwelding gun power block, said bore having an inwardly-facing boresurface, at least one of said first receiving structure and said secondreceiving structure having a projection extending therefrom or adepression extending thereinto, whereby, when said first and secondreceiving structures are aligned with each other, a respectiveinwardly-facing bore surface extends axially of the bore along a pathcontaining at least one discontinuity in a path direction.
 14. A weldinggun power block as in claim 13 wherein each of said first and secondreceiving structures comprises at least one projection extendingtherefrom or at least one depression extending thereinto.
 15. A weldinggun power block as in claim 13 wherein a receiving structure surface,bearing such discontinuity, is defined by a said projection removablyextending into at least one of said first and second receivingstructures.
 16. A welding gun power block as in claim 13, wherein saidprojection comprises a sliding arm having a generally straight-linedistal edge and removably extending into said bore through at least oneof said first and second receiving structures.
 17. A welding gun powerblock as in claim 13, wherein said projection comprises a sliding armhaving a generally arcuate distal edge thereby to cooperate with anarcuate outer surface of such welding gun power pin, and removablyextending into said bore through at least one of said first and secondreceiving structures.
 18. A welding system comprising a wire feederapparatus having a welding gun power block as in claim
 13. 19. A weldinggun power block for holding a welding gun power pin, said welding gunpower block comprising: (a) a welding gun power block base; and (b) awelding gun power pin holder having a power pin plate, said power pinplate having a main body, and a sliding arm extending therefrom, saidpower block base and said power pin holder, collectively, defining apower pin bore extending through said power block, said sliding armcommunicating with at least one of said power block base and said powerpin holder, and thereby extending into the power pin bore in said powerblock.
 20. A welding gun power block as in claim 19, said power pinplate being movable between at least a first position and a secondposition.
 21. A welding gun power block as in claim 20 wherein, whensaid power pin plate is in the first position, said sliding arm of saidpower pin plate generally extends into the power pin bore.
 22. A weldinggun power block as in claim 20 wherein, when said power pin plate is inthe second position, said sliding arm of said power pin plate generallydoes not extend into the power pin bore.
 23. A welding gun power blockas in claim 19, said sliding arm having a generally straight line distaledge.
 24. A welding gun power block as in claim 19, said sliding armhaving a generally arcuate distal edge.
 25. A welding system comprisinga wire feeder apparatus having a welding gun power block as in claim 19.